THE TREATMENT AND PROGNOSIS OF MEDULLOBLASTOMA IN CHILDREN

A STUDY OF 82 VERIFIED CASES

¹ From the Royal Marsden Hospital and Institute of Cancer Research, London, S.W.₃, England

A study has been made of 82 histologically verified cases of medulloblastoma under 15 years of age referred for irradiation to the Royal Marsden Hospital between 1950 and 1964. The age range was 11 months to 14 years. The ratio of boys to girls was 2.2:1.

The tempo of the disease is faster in children than in adults and the younger the patient the more rapidly will unsuccessful cases die. Survival rates are greater for girls than for boys. In some cases with brain-stem involvement radiotherapy can cure or control locally advanced disease for an appreciable time. There is no correlation between outcome and histologic grade of tumor. The survival rate is greater for patients in whom a "complete" surgical excision of the tumor was performed, compared with lesser procedures.

Of 68 unselected cases followed for 5 years, 22 (32 per cent) have survived, and of 34 cases, 9 (26 per cent) are alive at 10 years.

The treatment advised for medulloblastoma is surgical exploration with removal of as much of the tumor as possible without increasing unduly the operative risk. This must be followed by irradiation of the entire cerebrospinal axis. At present, a maximum dose to the cerebellum and brain-stem of 4,000-4,500 r in 6-7 weeks is recommended for children under 3 years, and 4,500-5,000 r in 6-7 weeks for older children. The "prophylactic" dose to the remainder of the brain falls from 4,000 r in the middle region to 3,000 r at the frontal poles. The spinal cord receives 2,000-2,500 r. The cases reported here have been treated with 250 kv. roentgen rays. Megavoltage equipment (6 mev.) is now being used for older children.

Although widespread intrathecal tumor is generally present in fatal cases, the chief cause of therapeutic failure in medulloblastoma is persistence or recurrence of tumor at the primary site.

The survival rate increases with higher radiation doses to the posterior fossa, but there may be an optimum level above which results deteriorate; with orthovoltage roentgen rays this level may be approximately 4,500 r.

All recurrences in this series obeyed Collins' law for embryonal tumors and produced symptoms within a period of time corresponding to the patient's age at treatment plus 9 months for gestation. Once a child with medulloblastoma passes this critical period safely, cure seems likely. Limited retreatment of tumor recurrence by irradiation in previously radically irradiated cases is justified and often brings worthwhile relief of distressing symptoms.

In spite of the many potential late complications in the central nervous system and extraneurologic tissues associated with cerebrospinal irradiation in young children with medulloblastoma, 18 of 22 patients (82 per cent) surviving 5 years had no serious disability and were leading active lives. Two children were partly disabled, and 2 others, treated at age 11 months and 15 months, respectively, were demented. Serious neurologic sequelae are more likely to be due to the original primary tumor and its associated hydrocephalus than to radiotherapy.

While the grave prognosis associated with medulloblastoma is fully justified, it appears that some hope can be given to parents of children with this disease, since practically 40 per cent of our cases completing treatment have survived 5 years, and 30 per cent, 10 years.

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